1. Technical Field
The present invention is a key lock for restricting operation of a pop-type handle on a container closure, such as a vending machine door, and more particularly is a pop-handle lock having improved tamper resistance features for defeating the efforts of unauthorized individuals to forcibly access the interior of the container.
2. Background Art
Pop-handle locks are used to secure the door of a vending machine or similar closure and prohibit unauthorized entry into the machine interior. A prior pop-handle lock is described in Spencer U.S. Pat. No. 3,299,678, issued Jan. 24, 1967, and is illustrated in FIG. 1 generally at 10.
The pop-handle lock 10 has a T-shaped housing 12 with openings 14 for receiving screws 16 for attaching the housing 12 to a vending machine door 18. The housing 12 is provided with a draw screw 19 extending therefrom and having a threaded end 20 for engagement with a mating nut 22 positioned in the interior of a vending machine 23, whereby securement of the vending machine door 18 with the vending machine 23 is achieved by threading the end 20 of the draw screw 19 into the nut 22. A T-shaped handle 24 having an axial shank 26 is seated within the housing 12.
A key-operated lock 28 has a retractable bolt 30 which projects through an opening 32 in the handle shank 26 and is received in an opening 34 in the housing 12 to hold the handle in a retracted, inoperable position, as shown in solid lines in FIG. 1. When the bolt 30 is retracted by means of an appropriate key, a biasing spring 36 pops the handle 24 axially outward of the housing 12 into an extended, operable position, as shown in phantom lines in FIG. 1. In the extended position of the handle 24, a notch 38 on the handle 24 engages a pin 40 on the draw screw 19, whereby the handle can be grasped and used to rotate the threaded shaft end 20 into and out of engagement with the nut 22 for respectively opening and closing the vending machine door 18.
Wolniak U.S. Pat. No. 3,438,227, issued Apr. 15, 1969, describes the manner in which the retractable bolt in a prior pop-handle lock is actuated.
Referring to the sectional view shown in FIG. 2, Wolniak '227 shows a key lock having a rotatable plug 42 disposed in a cylindrical lock barrel 44. A spring biased retractable bolt 46 extends radially through aligned openings in the lock barrel 44 and an axially movable handle 48. A housing 50 fixed to a closure 51 has a notch for receiving the bolt 46 when the key plug is in a locked position. The bolt 46 has a recess 52 for receiving a pin 54 which projects from the end of the key plug 42. A cam surface 53 on the recess 52 contacts the pin 54 when the key plug 42 is rotated to alternatively extend and retract the bolt 46 into and out of engagement, respectively, with the fixed housing 50.
Thieves have developed techniques for defeating the security offered by the prior pop-handle locks.
One technique which is used is that a hole is drilled through the lock or a portion of the door which surrounds the lock, and a stiff wire is inserted through the hole to engage the bolt and retract the bolt out of engagement with the T-handle and housing. The key lock and handle then are popped out of the housing by the biasing spring and the handle is used to open the vending machine door.
Another method in which existing pop-handle lock assemblies have been defeated is by driving a screw into the keyway on the rotatable key plug. The key plug then is forcibly extracted from the lock by prying the screw and attached lock components out of the door. With the key plug extracted, the bolt can be manually retracted to extend the handle and open the door.